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Author (up) Benisty, D.; Olmo, G.J.; Rubiera-Garcia, D. url  doi
openurl 
  Title Singularity-Free and Cosmologically Viable Born-Infeld Gravity with Scalar Matter Type Journal Article
  Year 2021 Publication Symmetry-Basel Abbreviated Journal Symmetry-Basel  
  Volume 13 Issue 11 Pages 2108 - 24pp  
  Keywords metric-affine gravity; non-singular cosmologies; born-infeld gravity; observational constraints; scalar fields  
  Abstract The early cosmology, driven by a single scalar field, both massless and massive, in the context of Eddington-inspired Born-Infeld gravity, is explored. We show the existence of nonsingular solutions of bouncing and loitering type (depending on the sign of the gravitational theory's parameter, epsilon) replacing the Big Bang singularity, and discuss their properties. In addition, in the massive case, we find some new features of the cosmological evolution depending on the value of the mass parameter, including asymmetries in the expansion/contraction phases, or a continuous transition between a contracting phase to an expanding one via an intermediate loitering phase. We also provide a combined analysis of cosmic chronometers, standard candles, BAO, and CMB data to constrain the model, finding that for roughly |epsilon|& LSIM;5 & BULL;10-8m2 the model is compatible with the latest observations while successfully removing the Big Bang singularity. This bound is several orders of magnitude stronger than the most stringent constraints currently available in the literature.  
  Address [Benisty, David] Univ Cambridge, Ctr Math Sci, DAMTP, Wilberforce Rd, Cambridge CB3 0WA, England, Email: benidav@post.bgu.ac.il;  
  Corporate Author Thesis  
  Publisher Mdpi Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000726717400001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5040  
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Author (up) Olmo, G.J.; Rubiera-Garcia, D. url  doi
openurl 
  Title Some recent results on Ricci-based gravity theories Type Journal Article
  Year 2022 Publication International Journal of Modern Physics D Abbreviated Journal Int. J. Mod. Phys. D  
  Volume 31 Issue Pages 2240012 - 15pp  
  Keywords Metric-affine gravity; scalar fields; stellar models; junction conditions; compact objects  
  Abstract In this paper, metric-afline theories in which the gravity Lagrangian is built using (projectively invariant) contractions of the Ricci tensor with itself and with the metric (Ricci-based gravity theories, or RBGs for short) are reviewed. The goal is to provide a contextualized and coherent presentation of some recent results. In particular, we focus on the correspondence that exists between the field equations of these theories and those of general relativity, and comment on how this can be used to build new solutions of physical interest. We also discuss the formalism of junction conditions in the f (R) case, and provide a brief summary on current experimental and observational bounds on model parameters.  
  Address [Olmo, Gonzalo J.] Univ Valencia, CSIC, Ctr Mixto, Dept Fis Teor, Valencia 46100, Spain, Email: gonzalo.olmo@uv.es;  
  Corporate Author Thesis  
  Publisher World Scientific Publ Co Pte Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0218-2718 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000848888900001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5350  
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